Variable thermal resistance structure and design method suitable for material irradiation temperature adjustment

Abstract

This invention relates to the field of reactor material irradiation technology. It provides a variable thermal resistance structure and design method suitable for adjusting the irradiation temperature of materials. The structure includes a protective tube and a sample to be tested placed inside the protective tube. An elastic thermal resistance is positioned between the protective tube and the sample, simultaneously contacting both. The cross-section of the elastic thermal resistance is a continuously bent annular structure. An inert gas is filled between the protective tube and the sample. By simultaneously contacting the outer wall of the sample and the inner wall of the protective tube with the elastic thermal resistance, the heat transfer of the original air gap layer is altered, enhancing heat transfer performance. Simultaneously, the bent elastic thermal resistance possesses a certain degree of ductility, enhancing the outward heat transfer capacity of the sample during irradiation testing while reducing the impact of thermal expansion on heat transfer, thus meeting diverse material irradiation testing requirements. Parameters are determined through off-pile verification tests, and combined with in-pile condition tests, a suitable elastic thermal resistance is quickly selected.

Description

Technical Field

[0001] This invention relates to the field of research reactor material irradiation technology, and more specifically, to a variable thermal resistance structure and design method suitable for adjusting the irradiation temperature of materials. Background Technology

[0002] With the advancement of nuclear energy technology, the research and development of new fuels and cladding materials faces diverse irradiation requirements, among which the temperature and neutron flux of irradiation tests are key indicators. As irradiation test tasks increase and requirements become more stringent, under certain specific operating conditions, the heat release parameters of the material may lead to an excessively small or large air gap size, rendering traditional temperature control methods inadequate for the needs of irradiation experiments.

[0003] Under irradiation conditions of high heat release rate and low irradiation temperature, the higher heat release rate requires higher gamma heat release and other conditions, leading to the selection of high neutron flux regions in research reactors for material irradiation. However, this approach, when employing air gap structure design, may result in insufficient air gap size, or even cause the material's irradiation temperature to be significantly higher than the target temperature. To address this issue, domestic and international researchers have employed media such as liquid sodium and liquid lead-bismuth, utilizing the excellent filling and thermal conductivity of liquid metals to enhance the heat transfer capacity during material irradiation, thereby achieving the target temperature. However, this method is only applicable to specific irradiation requirements such as liquid metal environments, and its applicability is relatively limited.

[0004] In certain high-temperature irradiation conditions, the air gap design for irradiation experiments using pure helium is relatively large. When a small amount of low thermal conductivity gas such as argon is introduced, the temperature fluctuation may be very drastic, thus affecting the temperature adjustability.

[0005] Therefore, in order to adapt to the development of nuclear energy technology and meet the diverse needs of material irradiation testing, it is particularly necessary to design a variable thermal resistance suitable for adjusting the irradiation temperature of materials. Summary of the Invention

[0006] The purpose of this invention is to provide a variable thermal resistance structure and design method suitable for adjusting the irradiation temperature of materials, which solves the above-mentioned technical problems, is highly flexible, has a wide range of applications, can meet the diverse material irradiation test requirements, and enhances heat transfer performance.

[0007] The present invention is achieved through the following technical solution: a variable thermal resistance structure suitable for adjusting the irradiation temperature of materials, including a protective tube and a sample to be tested disposed inside the protective tube, an elastic thermal resistance is provided between the protective tube and the sample to be tested, the elastic thermal resistance is in contact with both the protective tube and the sample to be tested, the cross-section of the elastic thermal resistance is a ring structure formed by continuous bending, and an inert gas is filled between the protective tube and the sample to be tested.

[0008] Furthermore, the elastic thermal resistance has an arch on the contact surface with the protective tube and the sample to be tested.

[0009] Furthermore, the cross-section of the smallest bending unit of the elastic thermal resistance is trapezoidal, V-shaped, U-shaped, or arc-shaped.

[0010] Furthermore, the thickness of the elastic thermal resistance is 0.05–0.1 mm.

[0011] Furthermore, the bending height of the elastic thermal resistance is 0.1–0.7 mm.

[0012] Furthermore, the elastic thermal resistance is made of a thermally conductive metal material.

[0013] Furthermore, the sample to be tested is in the shape of a round tube or a cylinder.

[0014] A design method comprising the following steps:

[0015] Step S1: Determine the size of the elastic thermal resistance based on the size, heat release and irradiation temperature requirements of the sample to be tested, and preliminarily screen the materials and bending forms of the elastic thermal resistance.

[0016] Step S2: Based on the screening results of Step S1, an off-pile verification test is used to screen the elastic thermal resistance that initially meets the requirements.

[0017] Step S3: Based on the screening results of step S2, the variation law of elastic thermal resistance under in-pile irradiation conditions is obtained by using in-pile condition tests.

[0018] Step S4: After optimizing and improving based on the above-mentioned change patterns, conduct subsequent formal experiments.

[0019] Furthermore, in the off-pile verification test, the elastic thermal resistance was held flat and kept continuously bent by a plate clamp. One side of the plate was equipped with a pressure measuring device for detecting the pressure that the elastic thermal resistance could withstand and a cooling system for simulating the cooling environment temperature. The other side of the plate was equipped with a heating system for simulating irradiation power conditions. The temperature change law of the elastic thermal resistance with pressure, power and cooling temperature factors was obtained respectively, and the elastic thermal resistance that met the test requirements was screened out.

[0020] Furthermore, in the in-pile condition test, based on the elastic thermal resistance screened by the off-pile verification test, an analog size simulation method was used to conduct a scale-up test in the in-pile according to the actual size of the target sample, and the temperature change law of the elastic thermal resistance in the scale-up test was obtained.

[0021] The present invention has at least the following advantages and beneficial effects:

[0022] (1) By simultaneously contacting the outer wall of the sample under test and the inner wall of the protective tube through the elastic thermal resistance, the heat conduction form of the metal is increased, the heat transfer of the original air gap layer is changed, and the heat transfer performance is enhanced. At the same time, the elastic thermal resistance formed by bending has a certain degree of extensibility, which not only enhances the heat transfer capacity of the sample under test to the outside during the irradiation test, but also reduces the influence of thermal expansion on heat transfer, thus meeting the diverse material irradiation test requirements.

[0023] (2) By adjusting the material, thickness, bending height and bending form of the elastic thermal resistor, the thermal conductivity, contact area and extensibility of the elastic thermal resistor are changed, so as to achieve the adjustability of the thermal resistance layer within a certain range.

[0024] (3) By setting an arch on the contact surface of the elastic thermal resistance, the contact changes between the elastic thermal resistance structure and the sample and the protective tube caused by thermal expansion can be further reduced, forming a stable thermal resistance layer and increasing the stability of the irradiation temperature.

[0025] (4) Parameters are determined through off-pile verification tests and combined with on-pile condition tests to quickly screen out the elastic thermal resistance that meets the requirements.

[0026] (5) By filling the space between the sample and the protective tube with inert gas and adjusting the composition of the inert gas, the adjustability of the thermal resistance layer can be further realized. It has a wide range of applications and meets the temperature control requirements. Attached Figure Description

[0027] Figure 1 This invention provides an installation schematic diagram of a variable thermal resistance structure suitable for adjusting the irradiation temperature of materials.

[0028] Figure 2 For the present invention Figure 1 A magnified view of a portion of point A in the middle.

[0029] Figure 3 This is a schematic diagram of one structural form of the minimum bending unit with elastic thermal resistance in this invention.

[0030] Figure 4 This is a schematic diagram of another structural form of the minimum bending unit with elastic thermal resistance in this invention.

[0031] Figure 5 This is a schematic diagram of another structural form of the minimum bending unit with elastic thermal resistance in this invention.

[0032] Figure labels: 1-protective tube, 2-sample to be tested, 3-elastic thermal resistance, 30-bend. Detailed Implementation

[0033] The specific implementation method is described below with reference to the accompanying drawings.

[0034] Example

[0035] like Figure 1 , 2 As shown in this embodiment, a variable thermal resistance structure suitable for adjusting the irradiation temperature of materials is disclosed, including a protective tube 1 and a sample 2 to be tested disposed within the protective tube 1. An elastic thermal resistance 3 is disposed between the protective tube 1 and the sample 2 to be tested, and the elastic thermal resistance 3 is in contact with both the protective tube 1 and the sample 2 to be tested. The cross-section of the elastic thermal resistance 3 is a continuously bent annular structure. An inert gas is also filled between the protective tube 1 and the sample 2 to be tested. It should be noted that there is an air gap between the protective tube 1 and the sample 2 to be tested, forming a thermal resistance layer. In this invention, an inert gas is pre-filled in the thermal resistance layer. The inert gas can be helium, argon, or neon. In addition, the inert gas is not limited to using a single gas, and multiple inert gases can also be used. The gas mixture can be used as a filler gas. According to the temperature requirements of the irradiation test, the temperature can be regulated and controlled by filling or changing the composition of the inert gas, so that the thermal resistance layer between the sample 2 and the protective tube 1 has a certain degree of variability. Specifically, the elastic thermal resistance 3 is made of thermally conductive metal material. The elastic thermal resistance 3 is rolled into a ring after continuous bending and placed between the sample 2 and the protective tube 1, which increases the thermal conductivity of the metal, changes the heat transfer of the original air gap layer, and enhances the heat transfer performance. At the same time, the elastic thermal resistance 3 formed by bending has a certain degree of ductility, which not only enhances the outward heat transfer capacity of the sample 2 in the irradiation test, but also reduces the influence of thermal expansion on heat transfer, thus meeting the diverse material irradiation test requirements.

[0036] Furthermore, in a specific implementation, the elastic thermal resistance 3 provided in the embodiment of the present invention has an arch 30 on the contact surface with the protective tube 1 and the sample to be tested 2; this can further reduce the contact influence between the elastic thermal resistance 3 structure and the sample to be tested 2 and the protective tube 1 caused by structural changes such as thermal expansion due to irradiation of the test sample, thereby forming a stable thermal resistance layer and increasing the stability of the irradiation temperature.

[0037] Furthermore, in specific implementations, the cross-section of the minimum bending unit of the elastic thermal resistance 3 provided in the embodiments of the present invention is trapezoidal, V-shaped, U-shaped, or arc-shaped. During the irradiation test, the sample 2 under test expands due to the increase in temperature, compressing the elastic thermal resistance 3. Through the above-mentioned structural form, the elastic thermal resistance 3 has a certain elasticity, which can reduce the large changes in the thermal resistance layer caused by the change in contact area due to thermal expansion during the irradiation test. It has a certain degree of robustness to structural changes, and in the application of pre-filled inert gas, it reduces the influence of structural changes on the irradiation temperature.

[0038] Furthermore, in specific implementation, the thickness of the elastic thermal resistance 3 provided in the embodiments of the present invention is 0.05 to 0.1 mm, and the bending height of the elastic thermal resistance 3 is 0.1 to 0.7 m. The parameters are determined according to the heat release and diameter of the sample to be tested. For example, when the diameter of the sample to be tested is small, the thickness and bending height of the elastic thermal resistance 3 are both smaller values. By appropriately adjusting the thickness and bending height of the elastic thermal resistance 3, the heat transfer performance of the irradiation test sample is changed to meet the requirements of the irradiation test.

[0039] Furthermore, in specific implementations, the above-described embodiments of the present invention are provided...

[0040] Furthermore, in specific implementation, the above-mentioned test sample 2 provided in the embodiments of the present invention is in the shape of a round tube or a cylinder.

[0041] In this embodiment, a design method based on a variable thermal resistance structure suitable for material irradiation temperature regulation is also disclosed. The overall idea is to initially select the elastic thermal resistance 3 material and bending form based on the target air gap structure and irradiation index. Different bending forms mainly correspond to different contact areas. Then, the selected materials and elastic thermal resistance 3 with different bending forms are further screened out of the reactor core through reduction simulation to select the elastic thermal resistance 3 material and bending form that meet the requirements. Next, in the reactor core, according to the actual size of the target sample, a scale-up test is conducted with the further selected materials and bending forms. Finally, the temperature change law of the elastic thermal resistance 3 measured inside and outside the reactor core is fitted, and appropriate adjustments are made (for example, the temperature change of the elastic thermal resistance 3 in the in-reactor test is greater than that in the out-of-reactor test, which can be achieved by changing the composition of the filling inert gas or reducing the contact area between the elastic thermal resistance 3 and the test sample 2 and the protective tube 1). The subsequent formal test can then be carried out, which mainly includes the following steps:

[0042] Step S1: Determine the size of the elastic thermal resistance 3 based on the size, heat release and irradiation temperature requirements of the sample to be tested 2, and preliminarily screen the material and bending form of the elastic thermal resistance 3; Specifically, two sets of test pieces are set up outside the pile and inside the pile respectively. The sample to be tested 2 here actually refers to the final target sample inside the pile.

[0043] Step S2: Based on the screening results of Step S1, an off-pile verification test is used to screen the elastic thermal resistance 3 that initially meets the requirements; that is, according to the selected material and bending form, a reduction simulation is first performed off-pile for further screening.

[0044] Step S3: Based on the screening results of step S2, the variation law of elastic thermal resistance 3 under in-pile irradiation conditions is obtained by using in-pile condition tests.

[0045] Step S4: After optimizing and improving based on the above-mentioned change patterns, conduct subsequent formal experiments.

[0046] Furthermore, in specific implementation, in the above-mentioned off-pile verification test provided in the embodiment of the present invention, the elastic thermal resistance 3 is held flat and continuously bent by a plate clamp. One side of the plate is equipped with a pressure measuring device for detecting the pressure borne by the elastic thermal resistance 3 and a cooling system for simulating the cooling environment temperature. The other side of the plate is equipped with a heating system for simulating irradiation power conditions. The temperature change law of the elastic thermal resistance 3 with pressure, power and cooling temperature factors is obtained respectively, and the elastic thermal resistance 3 that meets the test requirements is selected.

[0047] Furthermore, in specific implementation, in the above-mentioned in-pile condition test provided in the embodiments of the present invention, based on the elastic thermal resistance 3 screened by the off-pile verification test, an analog size simulation method is used to conduct an amplification test in the in-pile according to the actual size of the target sample, and the temperature change law of the elastic thermal resistance 3 in the amplification test is obtained.

Claims

1. A variable thermal resistance structure suitable for adjusting the irradiation temperature of materials, comprising a protective tube (1) and a sample to be tested (2) disposed within the protective tube (1), characterized in that, An elastic thermal resistor (3) is provided between the protective tube (1) and the sample to be tested (2). The elastic thermal resistor (3) is in contact with both the protective tube (1) and the sample to be tested (2). The cross-section of the elastic thermal resistor (3) is a ring structure formed by continuous bending. An inert gas is also filled between the protective tube (1) and the sample to be tested (2). The elastic thermal resistor (3) has an arch (30) on the contact surface with the protective tube (1) and the sample to be tested (2).

2. The variable thermal resistance structure suitable for adjusting the irradiation temperature of materials according to claim 1, characterized in that, The minimum bending unit cross-section of the elastic thermal resistance (3) is trapezoidal, V-shaped, U-shaped or arc-shaped.

3. A variable thermal resistance structure suitable for adjusting material irradiation temperature according to claim 1, characterized in that, The thickness of the elastic thermal resistor (3) is 0.05~0.1mm.

4. A variable thermal resistance structure suitable for adjusting material irradiation temperature according to claim 1, characterized in that, The bending height of the elastic thermal resistance (3) is 0.1~0.7mm.

5. A variable thermal resistance structure suitable for adjusting the irradiation temperature of materials according to claim 1, characterized in that, The elastic thermal resistance (3) is made of thermally conductive metal material.

6. A variable thermal resistance structure suitable for adjusting material irradiation temperature according to claim 1, characterized in that, The sample to be tested (2) is in the shape of a round tube or a cylinder.

7. A design method for a variable thermal resistance structure suitable for material irradiation temperature regulation based on any one of claims 1-6, characterized in that, Includes the following steps: Step S1: Determine the size of the elastic thermal resistance (3) based on the size, heat release and irradiation temperature requirements of the sample to be tested (2), and preliminarily screen the material and bending form of the elastic thermal resistance (3); Step S2: Based on the screening results of step S1, the elastic thermal resistance (3) that initially meets the requirements is screened by off-pile verification test; Step S3: Based on the screening results of step S2, the variation law of the elastic thermal resistance (3) under in-pile irradiation conditions is obtained by using in-pile condition test; Step S4: After optimizing and improving based on the above-mentioned change patterns, conduct subsequent formal experiments.

8. The design method according to claim 7, characterized in that, In the off-pile verification test, the elastic thermal resistance (3) is held flat by a plate and kept in a continuous bending state. One side of the plate is equipped with a pressure measuring device for detecting the pressure borne by the elastic thermal resistance (3) and a cooling system for simulating the cooling environment temperature. The other side of the plate is equipped with a heating system for simulating irradiation power conditions. The temperature change law of the elastic thermal resistance (3) with pressure, power and cooling temperature factors is obtained respectively, and the elastic thermal resistance (3) that meets the test requirements is selected.

9. The design method according to claim 7, characterized in that, In the in-pile condition test, based on the elastic thermal resistance (3) selected by the external verification test, an analog size simulation method is used to conduct an amplification test in the in-pile according to the actual size of the target sample, and the temperature change law of the elastic thermal resistance (3) in the amplification test is obtained.

Images